The present invention relates to threaded inserts used as attachment points in many applications, but particularly in sports equipment such a snowboards, sailboards, and certain surfboards. These inserts are typically a short cylindrical internally threaded plug, often with an integral base plate of somewhat larger diameter, embedded within the structure of the relatively thin board and serving as internally threaded anchors, accessible from a surface of the finished board, to which the bindings for the user""s feet are attached. Although sixteen threaded inserts are commonly used per board in a typical snowboard, as many as thirty-two may be used, to provide size and spacing accommodation.
Specifically with respect to snowboard use, there are several common difficulties encountered with products presently available in manufacturing. These difficulties relate to ease of assembly and cost. The boards are generally constructed of a core (usually wood) of appropriate shape, into which the attachment inserts are fitted. A finish layer or laminate is applied to the outer surfaces (e.g. top and bottom) of the core and the whole assembly is cured, for example in a heated press. The outer surface at this point usually contains coloring, decoration, etc., which covers and conceals the internally contained inserts. Thus, various visual marking schemes for revealing insert location are not readily compatible with the over all manufacturing process.
Typically, in this manufacturing sequence counterbored holes or insert cavities are formed in the core material (usually wood) by a step drill. The inserts are positioned in these holes and the top and bottom of the core material, covered with the completing exterior layers or laminates of the snowboard, and the included inserts, are then simultaneously bonded into a single assembly with a thermosetting resin cured under pressure. In order to prevent resin from infiltrating the threaded cavity of the inserts, the inserts are provided with a cap or plug to be subsequently removed, for example drilled out, to exposed the threaded sockets afforded by the inserts after resin cure.
Difficulties arise in locating the embedded inserts in the final snowboard assembly in order to drill out such caps or plugs. If the board has been manufactured in a fully numerically controlled manner with suitable geometric locating features and corresponding jigs and equipment, insert location can be determined mathematically. This method, while potentially accurate is inherently expensive to establish.
What is needed is a simple, inexpensive solution to the problem of embedded insert location for cap drilling that simplifies manufacturing without compromising the manufacturability and cost of inserts.
A more accessible approach is provided by this invention using temporary formation of visible magnetic field lines. If the inserts are themselves made of a material which is capable of concentrating magnetic lines of force, a magnet can be positioned beneath the board and fine iron powder sprinkled on the top of the board, above the capped or plugged inserts. The location of the inserts will then be revealed in telltale patterns formed in the iron powder by the magnetic field lines concentrated about the inserts. While this method can serve the needs of a manufacturer, it requires that the manufacturer possess equipment to produce strong magnetic fields, and use such equipment in a separate locating step in the process. The manufacturer""s choice of insert material is limited to insert materials that will concentrate a magnetic force field. Thus it is beneficial that the insert assembly itself have the capability to create a force field, and this can be accomplished with a permanent magnet associated with the insert in some manner.
Thus the present invention provides a novel insert assembly for use in snowboards and other sporting equipment that provides for embedded insert location, regardless of the properties of the insert material per se, and without requiring either expensive equipment or a complex location process.
The objects of the invention are achieved by positioning a small inexpensive magnet on or within the insert itself, as by use of a small permanent magnet attached to the cap, or by use of a magnetic cap to cover the insert cavity, or placing a plug-like magnet in the open threaded end of the inserts. After the board assembly is complete, a magnetic material such as iron powder is dusted on the surface of the board to react with the field lines created about each insert, revealing the insert location. Then, the board can be drilled to pierce the insert cap, and facilitate removal of any plug in the insert. It is also possible to provide, through powdered metal technology, an insert material which itself will produce the desired magnetic field of sufficient intensity at the dusted surface of the board.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.